
# How to use PostProcessRenderPipeline
Post Process Renders pipelines allow you to create a chain of post processes and attach it to a camera.
A render pipeline can be managed by enabling and disabling some effects and displaying a specific pass for debugging.


## Base Render Pipeline

![](/img/PPArchitecture.png)

Renders Pipelines are composed of several classes.

| Class | Description |
|--------|--------|
|**`BABYLON.PostProcessRenderPipelineManager`**| Managing all pipelines, allow you to enable or disable an effect, displaying a pass of post process for debugging.|
|**`BABYLON.PostProcessRenderPipeline`**|Set of effects that can be ordered.|
|**`BABYLON.PostProcessRenderEffect`**|A render effect contains one or more post processes.|
|**`BABYLON.PostProcess`**|A render pass which will apply a shader.|

## Let's play with Render Pipeline

### Simple Pipeline
Create pipeline
```javascript
var standardPipeline = new BABYLON.PostProcessRenderPipeline(engine, "standardPipeline");
```

Create post processes. Note: Camera parameter is set to when using a pipeline and post process will be enabled when the pipeline is added to the camera.
```javascript
var blackAndWhite = new BABYLON.BlackAndWhitePostProcess("bw", 1.0, null, null, engine, false);
var horizontalBlur = new BABYLON.BlurPostProcess("hb", new BABYLON.Vector2(1.0, 0), 20, 1.0, null, null, engine, false);
```

Create an effect with multiple post processes
```javascript
var blackAndWhiteThenBlur = new BABYLON.PostProcessRenderEffect(engine, "blackAndWhiteThenBlur", function() { return [blackAndWhite, horizontalBlur] });
standardPipeline.addEffect(blackAndWhiteThenBlur);
```

Add pipeline to the scene's manager and attach to the camera
```javascript
scene.postProcessRenderPipelineManager.addPipeline(standardPipeline);
scene.postProcessRenderPipelineManager.attachCamerasToRenderPipeline("standardPipeline", camera);
```

<Playground id="#QCGFI6" title="Post Process Render Pipeline Example" description="Simple example of using a post process render pipeline."/>


# How To Use the SSAO rendering pipeline

BABYLON.SSAORenderingPipeline is a rendering pipeline (chained post-processes) that will compute the ambient occlusion of a given scene from the screen space.
You can find an example in our playground:

<Playground id="#N96NXC" title="SSAO Rendering Pipeline Example" description="Simple example of using the SSAO rendering pipeline."/>

The post-processes chain is defined by:

* Original scene color post-process: saves the original scene color
* SSAO post-process
* Horizontal blur post-process
* Vertical blur post-process
* Combine post-process: blends the Vertical blur post-process output with the original scene color

Using it is pretty straightforward:

```javascript
var ssao = new BABYLON.SSAORenderingPipeline('ssaopipeline', scene, 0.75);
```

The third argument is the ratio used by SSAO, Horizontal blur and Vertical blur post-processes
You can also set an array of Camera as fourth argument, then the constructor will automatically attach the rendering pipeline to the given cameras like:

```javascript
var ssao = new BABYLON.SSAORenderingPipeline('ssaopipeline', scene, 0.75, [camera1 etc.]);
```

If you want to attach manually the rendering pipeline, just use the scene rendering pipeline manager like:

```javascript
var ssao = new BABYLON.SSAORenderingPipeline('ssaopipeline', scene, 0.75);
scene.postProcessRenderPipelineManager.attachCamerasToRenderPipeline("ssaopipeline", cameras);
```

**Warning: To save your performances, you should compute the SSAO/blurH/blurV with a lower ratio than 1.0 **

If you want to detach and destroy the rendering pipeline, you can just call `dispose()` method
```javascript
ssao.dispose();
```

You can see the SSAO post-process output by detaching the combine post-process like:

```javascript
scene.postProcessRenderPipelineManager.disableEffectInPipeline("ssaopipeline", ssao.SSAOCombineRenderEffect, cameras);
```

**Note: SSAO uses the depth map renderer and activates it by default. You can disable the depth map renderer by passing "true" as argument in the dispose() method **

For more customization, you can specify the SSAO and Combine post-processes ratios like:

```javascript
var ssao = new BABYLON.SSAORenderingPipeline('ssaopipeline', scene, { ssaoRatio: 0.5, combineRatio: 1.0 }, [camera1 etc.]);
```


# How To Use PostProcess

## Base postprocess
Every postprocess is based upon ```BABYLON.PostProcess``` which uses this constructor:

```javascript
BABYLON.PostProcess = function (name, fragmentUrl, parameters, samplers, ratio, camera, samplingMode, engine, reusable)
```

We will get back to _fragmentUrl_, _parameters_ and _samplers_ parameters.

The _ratio_ is used to define the size of the postprocess (0.5 means that your postprocess will have a width = canvas.width * 0.5 and a height = canvas.height * 0.5).

The _camera_ parameter specifies which camera to attach to. If you're creating a post process that will be managed by a render pipeline, this should be set to null. See [Post Process Pipeline](/features/divingDeeper/postProcesses/postProcessRenderPipeline)

The _samplingMode_ can be one of the following:
* BABYLON.Texture.NEAREST_SAMPLINGMODE
* BABYLON.Texture.BILINEAR_SAMPLINGMODE (**default**)
* BABYLON.Texture.TRILINEAR_SAMPLINGMODE

Please note that postprocesses with trilinear sampling will be forced to have a power of two size (256, 512, 1024, etc.)

The _engine_ parameter is the engine where you want to attach your postprocess.

The _reusable_ parameter indicates if your postprocess can be reused multiple times on the same camera (default is false).

## Additional parameters
By default (and if you are not using trilinear sampling) postprocesses use the size of the screen scaled by the ratio you provide. But you can decide to force them to be rescaled to a power of two size in order to be more efficient. To enable this, just call `mypostprocess.alwaysForcePOT = true`.

You can also control how the size is chosen by setting `mypostprocess.scaleMode` to one of these values:
* BABYLON.Engine.SCALEMODE_FLOOR: Will find the next lowest power of two.
* BABYLON.Engine.SCALEMODE_NEAREST: Will find the nearest power of two.
* BABYLON.Engine.SCALEMODE_CEILING: Will find the next highest power of two.

You can also control if the postprocess is cleared upon rendering with `mypostprocess.autoClear = true`. This is the default behavior.

If you turn off autoClear, you will be able to blend the render of the postprocess with its previous content by defining an alphaMode with `mypostprocess.alphaMode = BABYLON.Engine.ALPHA_COMBINE`.

This could be really useful when you have multiple postprocesses enabled together. You can even choose to share the output of several postprocesses with `mypostprocess.shareOutputWith(anotherPostprocess)`.

## Attach postprocess
Depending on how you have defined a postprocess, it can be attached one or more times to the same camera.
The same instance can also be attached to multiple cameras.

A camera has two methods:
### **attachPostProcess**

```javascript
NUMBER function(PostProcess postProcess [,NUMBER atIndice])
```

### **detachPostProcess**

```javascript
NUMBER function(PostProcess postProcess [,NUMBER[] atIndices])
```

## Builtin postprocesses
Babylon.js comes with a set of ready to use postprocesses.

## Pass
Do nothing. Used to copy the framebuffer into a postprocess for further use

```javascript
var postProcess = new BABYLON.PassPostProcess("Scene copy", 1.0, camera);
```

### Black and white
Apply a black and white effect:

```javascript
var postProcess = new BABYLON.BlackAndWhitePostProcess("bandw", 1.0, camera);
```

## Blur
Apply a directional blur using a kernel based blur:

```javascript
var postProcess = new BABYLON.BlurPostProcess("Horizontal blur", new BABYLON.Vector2(1.0, 0), kernel, 0.25, camera);
```

The kernel value will define the ideal number of taps done by the postprocess. The postprocess will then adapt the kernel based on screen size and DPI resolution.

For instance here is an example with a kernel value of 32: <Playground id="#FBH4J7#3" title="Blur Post Process Example" description="Simple example of a blur post process."/>
Or 256: <Playground id="#FBH4J7#4" title="Blur Post Process With Kernal Value Of 256" description="Simple example of a blur post process with a kernal value of 256."/>

Obviously, as usual, try to stay reasonable with kernel size as it will impact the overall rendering speed.

### Convolution
Apply a kernel matrix to every pixel:

```javascript
var postProcess = new BABYLON.ConvolutionPostProcess("Sepia", BABYLON.ConvolutionPostProcess.EmbossKernel, 1.0, camera);
```

## FXAA
Apply a full screen antialiasing filter:

```javascript
var postProcess = new BABYLON.FxaaPostProcess("fxaa", 1.0, camera);
```

### Highlights
Apply a full screen highlight filter which will increment the luminosity of highlights in your scene:

```javascript
var postProcess = new BABYLON.HighlightsPostProcess("highlights", 1.0, camera);
```

### Tonemap
Apply a full screen tone mapping filter:

```javascript
var postProcess = new BABYLON.TonemapPostProcess("tonemap", BABYLON.TonemappingOperator.Hable, 1.0, camera);
```
The second parameter defines which operator will be used among the following ones:
* BABYLON.TonemappingOperator.Hable
* BABYLON.TonemappingOperator.Reinhard
* BABYLON.TonemappingOperator.HejiDawson
* BABYLON.TonemappingOperator.Photographic

The third parameter defines the exposure adjustment.

You can find a demo here: <Playground id="#J9H084#8" title="Tonemap Post Process" description="Simple Example of a tonemap post process."/>

### ImageProcessing
Apply a complete range of special image treaments (image processing):

```javascript
var postProcess = new BABYLON.ImageProcessingPostProcess("processing", 1.0, camera);
```

You have several options available:
* colorGradingTexture: Used to provide a color grading texture applied on your scene. You can use:
    * a [colorGradingTexture](/typedoc/classes/babylon.colorgradingtexture) using a [.3dl](https://en.wikipedia.org/wiki/3D_lookup_table) format. Demo: <Playground id="#17VHYI#15" title="ColorGrading Texture Post Process" description="Simple example of a colorgrading texture post process."/>
    * a standard texture (using .png for example) but with _invertY_ set to _true_, wrap mode as clamp and _imageProcessingConfiguration.colorGradingWithGreenDepth_ set to _false_. Demo: <Playground id="#17VHYI#9" title="ColorGrading Texture Post Process Green Depth" description="Simple example of a colorgrading texture post process."/>
* colorCurves: Used to provide several properties to change colors. More [details here](/features/divingDeeper/materials/using/masterPBR). Demo: <Playground id="#J9H084#12" title="ColorCurves Post Process" description="Simple example of a colorCurves post process."/>
* contrast: 1.0 by default. Used to change the contrast. Demo: <Playground id="#J9H084#9" title="colorCurves Post Process (Contrast)" description="Simple example of changing the the contrast of a colorCurves Post Process."/>
* exposure: 1.0 by default. Used to change the exposure of the image. Demo: <Playground id="#J9H084#10" title="colorCurves Post Process (Exposure)" description="Simple example of changing the exposure of a colorCurves Post Process."/>

You can also use this postprocess to enable a vignette effect. The vignette is positioned thanks to the following parameters:
* vignetteStretch: 0 by default
* vignetteCentreX: X coordinate of the center (0,0 is the center of the screen)
* vignetteCentreY: Y coordinate of the center (0,0 is the center of the screen)
* vignetteWeight: 1.5 by default
* vignetteColor: Color4 value to define the overall color
* vignetteBlendMode: BABYLON.ImageProcessingPostProcess.VIGNETTEMODE_MULTIPLY or BABYLON.ImageProcessingPostProcess.VIGNETTEMODE_OPAQUE

You can find a demo of the vignette here: <Playground id="#J9H084#11" title="Vignette Post Process" description="Simple example of a Vignette Post Process."/>

All features can be turned on and off with the following booleans:
* colorCurvesEnabled
* vignetteEnabled
* cameraToneMappingEnabled
* colorGradingEnabled

#### Configuration

Image postprocessing can be done with the ImageProcessingPostProcess, but you can also use the built-in image processing features in StandardMaterial and PBRMaterial. To simplify the overall configuration of your image processing setup, you can define the properties you want on `scene.imageProcessingConfiguration`.
This object hosts the same properties as the ImageProcessingPostProcess.

By default, ImageProcessingPostProcess, StandardMaterial and PBRMaterial share the same configuration object (The one from the scene). This means that if you change a value on `scene.imageProcessingConfiguration` or directly on ImageProcessingPostProcess, StandardMaterial or PBRMaterial, this will affect all entities sharing the same configuration.

Here is an example of a global configuration: <Playground id="#J9H084#13" title="Post Process Global Configuration" description="Simple example of a post process global configuration."/>

Furthermore, as they share the same configuration, you can just dispose a postprocess you were using and automatically the image processing will be done at materials level. So here is an example of a configuration done at scene level, but with no postprocess to use it: <Playground id="#J9H084#14" title="Configuration At The Scene Level" description="Simple example of a scene level configuration."/> (As you can see the processing is then done by the material itself).

You can also decide to instantiate your own configuration and affect it to your material or to your postprocess with `postProcess.imageProcessingConfiguration = new BABYLON.ImageProcessingConfiguration()`. In this case, you will be able to configure this object independantly.

*Troubleshoot*
If you use post-processes with built-in image processing features, you might run into brighter color issues.  
Read [this](/features/divingDeeper/materials/shaderss/image_processing#tonemapping) if you want to know how to fix it.

#### Default rendering pipeline

The image processing post process is also included in a rendering pipeline: the DefaultRenderingPipeline. This pipeline adds support for FXAA and bloom on top of the image processing. You can find a complete interactive demo here: <Playground id="#5XB8YT#1" title="Default Rendering Pipeline Featuring Bloom" description="Simple example of the default rendering pipeline with bloom."/>

You can turn pipeline features on and off with the following booleans:
* fxaaEnabled
* bloomEnabled
* imageProcessingEnabled

## Refraction
Apply a refraction texture:

```javascript
var postProcess = new BABYLON.RefractionPostProcess("Refraction", "refMap.jpg", new BABYLON.Color3(1.0, 1.0, 1.0), 0.5, 0.5, 1.0, camera);
```
The constructor of this postprocess is the following:

```javascript
BABYLON.RefractionPostProcess = function (name, refractionTextureUrl, color, depth, colorLevel, ratio, null, samplingMode, engine, reusable)
```
_refractionTextureUrl_ is the URL of the refraction map. The luminance of every pixel is used to define the refraction level (white = min, black = max)
_color_ is the base color of the refraction (used to taint the rendering)
_depth_ is the simulated refraction depth
_colorLevel_ is the coefficient of the base color (0 to remove base color tainting)

## Color Correction
Apply a color filter:

```javascript
var postProcess = new BABYLON.ColorCorrectionPostProcess("color_correction", "./table.png", 1.0, camera);
```
The second parameter of the constructor is the URL of the color look-up table (also known as _LUT_) that contains the filter to apply. This must be a texture 16 pixels high and 256 pixels wide containing a modified set of RGB colors (x=red value, y=green value, z=blue value). The post-processing will then map the RGB values of the rendered pixels to the new values contained in the look-up table.

Here is what the default (without filter) look-up table looks like:

![LUT](/img/how_to/post-processes/lut-default.png)

Examples of filtered LUT to use for various filters:

![LUT](/img/how_to/post-processes/lut-inverted.png)
 Inverted colors

![LUT](/img/how_to/post-processes/lut-highcontrast.png)
 High contrast

![LUT](/img/how_to/post-processes/lut-posterized.png)
 Posterize

You can easily create new filters by using a image editing software to alter the look-up table to fit your needs. Copy/paste the default look-up table on a screenshot or picture before altering it to see in real time what the filtered image will look like.

## Custom postprocesses
You can also develop your own postprocess using ```BABYLON.PostProcess``` object.

To do so, you need to create a .fragment.fx file, a shader-storing DOM node, or a ShaderStore entry where you will store the GLSL shader code used for every pixel of the screen:

```javascript

precision highp float;

// Samplers
varying vec2 vUV;
uniform sampler2D textureSampler;

// Parameters
uniform vec2 screenSize;
uniform float highlightThreshold;

float highlights(vec3 color)
{
 return smoothstep(highlightThreshold, 1.0, dot(color, vec3(0.3, 0.59, 0.11)));
}

void main(void)
{
 vec2 texelSize = vec2(1.0 / screenSize.x, 1.0 / screenSize.y);
 vec4 baseColor = texture2D(textureSampler, vUV + vec2(-1.0, -1.0) * texelSize) * 0.25;
 baseColor += texture2D(textureSampler, vUV + vec2(1.0, -1.0) * texelSize) * 0.25;
 baseColor += texture2D(textureSampler, vUV + vec2(1.0, 1.0) * texelSize) * 0.25;
 baseColor += texture2D(textureSampler, vUV + vec2(-1.0, 1.0) * texelSize) * 0.25;
 
 baseColor.a = highlights(baseColor.rgb);

 gl_FragColor = baseColor;
}
```

Your shader must define the following values:
* Precision must be set to highp
* A varying vUV must be used to read texture coordinates
* The first sampler must be named textureSampler

Once you created your sampler, you can create a postprocess:

```javascript
var postProcess = new BABYLON.PostProcess("Down sample", "./Scenes/Customs/postprocesses/downsample", ["screenSize", "highlightThreshold"], null, 0.25, camera);
```

You have to specify:
* A name
* The URL of the shader coder*
* A list of your uniforms parameters
* A list of additional samplers
* The ratio
* The parent camera (deprecated)
* The sampling mode
* The engine
* Can be reusable

(*Please see the link at the bottom of this document to learn more ways to store shader code.)

You can set up things before the postprocess is applied by specifying a onApply function:

```javascript
postProcess.onApply = function (effect) {
    effect.setFloat2("screenSize", postProcess1.width, postProcess1.height);
    effect.setFloat("highlightThreshold", 0.90);
};
```

You can find another example here: <Playground id="#DAC1WM" title="Custom Post Process Example" description="Simple example of a custom post process."/>

To use the output of a previous post process setTextureFromPostProcess can be used.
Note: This will set sceneSampler to the output of the post process before postProcess0 NOT the output of postProcess0.
```javascript
effect.setTextureFromPostProcess("sceneSampler", postProcess0);
```

## Chaining postprocesses
You can chain postprocesses on a specific camera. They are processed using the creation order. For instance here is the code used to simulate a bloom effect:

```javascript
var blurWidth = 1.0;

var postProcess0 = new BABYLON.PassPostProcess("Scene copy", 1.0, camera);
var postProcess1 = new BABYLON.PostProcess("Down sample", "./Scenes/Customs/postprocesses/downsample", ["screenSize", "highlightThreshold"], null, 0.25, camera, BABYLON.Texture.BILINEAR_SAMPLINGMODE);
postProcess1.onApply = function (effect) {
    effect.setFloat2("screenSize", postProcess1.width, postProcess1.height);
    effect.setFloat("highlightThreshold", 0.90);
};
var postProcess2 = new BABYLON.BlurPostProcess("Horizontal blur", new BABYLON.Vector2(1.0, 0), blurWidth, 0.25, camera);
var postProcess3 = new BABYLON.BlurPostProcess("Vertical blur", new BABYLON.Vector2(0, 1.0), blurWidth, 0.25, camera);
var postProcess4 = new BABYLON.PostProcess("Final compose", "./Scenes/Customs/postprocesses/compose", ["sceneIntensity", "glowIntensity", "highlightIntensity"], ["sceneSampler"], 1, camera);
postProcess4.onApply = function (effect) {
    effect.setTextureFromPostProcess("sceneSampler", postProcess0);
    effect.setFloat("sceneIntensity", 0.5);
    effect.setFloat("glowIntensity", 0.4);
    effect.setFloat("highlightIntensity", 1.0);
};
```
You might want to [read more about shaders](https://web.archive.org/web/20190904224946/https://www.eternalcoding.com/what-do-you-mean-by-shaders-learn-how-to-create-shaders-with-babylon-js/) and try our [CYOS shader editor](https://cyos.babylonjs.com/).


Class	Description
Class `BABYLON.PostProcessRenderPipelineManager`	Description Managing all pipelines, allow you to enable or disable an effect, displaying a pass of post process for debugging.
Class `BABYLON.PostProcessRenderPipeline`	Description Set of effects that can be ordered.
Class `BABYLON.PostProcessRenderEffect`	Description A render effect contains one or more post processes.
Class `BABYLON.PostProcess`	Description A render pass which will apply a shader.

How To Use A Post Process Render Pipeline

Base Render Pipeline

Let's play with Render Pipeline

Simple Pipeline